import { afterEach, describe, expect, it } from "vitest";
import {
  ANNOUNCER_ROOT_ID,
  announce,
  ensureAnnouncerRegions,
} from "./liveAnnouncer";

const NBSP = String.fromCharCode(0xa0);

const root = () => document.getElementById(ANNOUNCER_ROOT_ID);
const polite = () => document.getElementById(`${ANNOUNCER_ROOT_ID}-polite`);
const assertive = () =>
  document.getElementById(`${ANNOUNCER_ROOT_ID}-assertive`);

afterEach(() => {
  root()?.remove();
});

describe("ensureAnnouncerRegions", () => {
  it("mounts both regions empty so assistive tech registers them before any message", () => {
    ensureAnnouncerRegions();

    expect(polite()?.textContent).toBe("");
    expect(assertive()?.textContent).toBe("");
  });

  it("is idempotent", () => {
    const first = ensureAnnouncerRegions();
    const second = ensureAnnouncerRegions();

    expect(first).toBe(second);
    expect(document.querySelectorAll(`#${ANNOUNCER_ROOT_ID}`)).toHaveLength(1);
  });

  it("fixes politeness per region instead of swapping it on one node", () => {
    ensureAnnouncerRegions();

    expect(polite()?.getAttribute("role")).toBe("status");
    expect(polite()?.getAttribute("aria-live")).toBe("polite");
    expect(assertive()?.getAttribute("role")).toBe("alert");
    expect(assertive()?.getAttribute("aria-live")).toBe("assertive");
  });
});

describe("announce", () => {
  it("writes polite messages to the polite region by default", () => {
    announce("Settings saved.");

    expect(polite()?.textContent).toBe("Settings saved.");
    expect(assertive()?.textContent).toBe("");
  });

  it("routes assertive messages to the assertive region and clears the polite one", () => {
    announce("Settings saved.");
    announce("Could not save settings.", "assertive");

    expect(assertive()?.textContent).toBe("Could not save settings.");
    expect(polite()?.textContent).toBe("");
  });

  it("re-announces an identical consecutive message by alternating a trailing NBSP", () => {
    // A repeated "Settings saved." must still mutate the region"s text, or the
    // screen reader stays silent on every save after the first.
    announce("Settings saved.");
    const first = polite()?.textContent;

    announce("Settings saved.");
    const second = polite()?.textContent;

    announce("Settings saved.");
    const third = polite()?.textContent;

    expect(first).toBe("Settings saved.");
    expect(second).toBe(`Settings saved.${NBSP}`);
    expect(third).toBe("Settings saved.");

    expect(second).not.toBe(first);
    expect(third).not.toBe(second);
  });

  it("alternates across regions too, so a repeated error still announces", () => {
    announce("Could not save settings.", "assertive");
    const first = assertive()?.textContent;

    announce("Could not save settings.", "assertive");
    const second = assertive()?.textContent;

    expect(first).toBe("Could not save settings.");
    expect(second).toBe(`Could not save settings.${NBSP}`);
  });

  it("clears both regions on an empty message and forgets the last message", () => {
    announce("Settings saved.");
    announce("");

    expect(polite()?.textContent).toBe("");
    expect(assertive()?.textContent).toBe("");

    announce("Settings saved.");
    expect(polite()?.textContent).toBe("Settings saved.");
  });

  it("creates the regions on demand when nothing mounted them first", () => {
    expect(root()).toBeNull();

    announce("Settings saved.");

    expect(root()).not.toBeNull();
    expect(polite()?.textContent).toBe("Settings saved.");
  });
});